Chair back rest



FIG. 1 is a perspective view showing my new design;

FIG. 2 is a top view;

FIG. 3 is a front view;

FIG. 4 is a right side view, left side is a mirror image thereof;

FIG. 5 is a back view; and,

FIG. 6 is a bottom view.

The broken line showing of a chair in FIG. 1 is for illustrativepurposes only and forms no part of the claimed design.

The ornamental design for chair back rest, as shown and described.